1. Field
The present disclosure relates to a color characterization of color printers. More precisely, the present disclosure relates to the identification and selection of colorant combinations for color patches in a color characterization target, which is printed by a printer and which contains multiple different color patches, and which is measured colorimetrically or spectrally so as to color-characterize the printer.
2. Description of the Related Art
Known techniques for color-characterization of a color printer typically involve the printout by the printer of a color characterization target which contains multiple differently colored patches. The color patches are measured calorimetrically or spectrally. Based on a mapping between the colorant values that created each color patch, and the spectral or colorimetric measurement of each such color patch, the color performance of the printer can be derived and characterized.
Recently, two technological and marketplace developments have converged that tend to increase the burden involved in characterization of a color printer. First, more printers are being encountered that include a large number of colorant channels, such as CMYKRG color printers which include six color channels (i.e., cyan, magenta, yellow, black, red and green colorant channels). The number of color patches that must be printed increases geometrically with the number of colorant channels, for the reason that color characterization yields better results when the colors of the color patches fill the color space of the color printer. In addition, each color patch must be measured calorimetrically or spectrally. The complexity of the mapping between colorant values and color measurements also increases with an increased number of color patches. As a result, with four or more colorant channels, the burden of printing multiple patches, measuring them, and mapping them, also increases geometrically.
Second, there has been a trend toward spectral measurements and spectral characterization of color printers, as opposed to colorimetric measurements and colorimetric characterization. A colorimetric measurement of a color patch ordinarily yields a three-dimensional value such as a trichromatic XYZ value in CIEXYZ space or an L*a*b* value in CIELAB space. Spectral color measurements typically have far higher dimensionality. For example, a spectral measurement may include 31 measurements, each corresponding to a different measurement of the color patch's spectral reflectance at each 10 nm interval in the visible light range of 400 to 700 nm. The amount of data increases significantly with spectral measurements compared to colorimetric measurements. In addition, the complexity of the mapping between the colorant values and the spectral measurements is also increased significantly.